Color temperature is a kind of visible light that has important applications in lighting. The color temperature of a light source is the temperature of an ideal black-body radiator that radiates light of comparable hue to that of the light source. Color Temperature is a measurement in Degrees Kelvin that indicates the hue of a specific type of light source, the symbol of unit is K.

Different color temperature light of source also offer different light color, it will bring you a different feeling:

Higher color temperatures (5000K or more) are "cold", color is green to blue.

Good build quality bright like a 100w standard bulb
I just received it today and I was thinking that it PERFECT bright.
The light is a PERFECT bright, not yellowish like halogen or tungsten bulb.
It glow like a 1000 w standard bulb an take half a second to work after you light up the switch.
The construction quality seem good. It feel sturdy. Probably worth the price for country where the electricity cost a lot.
Where I live, the electricity is very low priced and the price difference with a standard bulb
is to high to be a good replacement choice. I bought it just because I like new technology ;)

Good build quality bright like a 100w standard bulb
I just received it today and I was thinking that it PERFECT bright.
The light is a PERFECT bright, not yellowish like halogen or tungsten bulb.
It glow like a 1000 w standard bulb an take half a second to work after you light up the switch.
The construction quality seem good. It feel sturdy. Probably worth the price for country where the electricity cost a lot.
Where I live, the electricity is very low priced and the price difference with a standard bulb
is to high to be a good replacement choice. I bought it just because I like new technology ;)

I installed these as replacements for external incandescent (standard) bulbs around the house, and they give me the light of a 60 watt bulb.
So, each bulb that is on for 12 hours a day using 720 watts is now using 120 watts - or 1/6 of the electricity cost - I could run SIX of these LED bulbs for the electricity cost of ONE incandescent.
In addition, I'm in Canada, where the current temperatures (mid-January) are down to minus 16 C (or close to zero F, or 32 degrees below freezing), and they are both still operating just fine in these extremes.
Highly recommended...
And don't get alarmed if you see they are still glowing like a hot corn husk an hour or more after they are turned off. The squares are just phosphorescing (glowing from the previous light emissions, like a TV monitor), and are NOT using any more electricity after being switched off.